Carbonization



A. H. ANDERsEN ETAL 2,380,930

GARBONIZATION Aug. 7, 41945.

Filed oct. 5., 1942 2 sheets-sneeti Aug. 7, 1945, A. H. ANDERSEN ETAL 2,380,930

' CARBONIZATION Filed Oct. 5, l1942 2 Sheets-Sheet 2 9v om om w 9.@

Sv. -..Y

Patented Aug. 7, 1945 cAaBomzs'rIoN Arthur I-Ioijord Andersen and Norman Rothwell Fasken, Shawinigan Falls, Quebec, Canada, assignors to Shawinigan Chemicals Limited, Montreal, Quebec, Canada, a corporation of Canalla.` -`Application October 5, 1942, Serial No. 460,802 In Canada July 16, 1942 v s claims. (c1. 2oz-s) Inrnoouc'rrox l 4 This invention' relates to carbonization. More particularlylt relates to improvements on a continuous carbonization process in which a relatively thin bed o! carbonizable material, usually coal, is passed through a substantially horizontal chamberwherein a portion ofthe volatile of the charge is burned at least partially within the bed to supply the heat .for removal of remaining volatile. The air supply, the speed of the bed, and other conditions are so regulated that the burning of xed carbon is reduced substantially to a minimum and a. high grade of coke is produced. A process of this type is disclosed in U. S.

Patent No. 2,209,255.

This type of method contrasts with previous 'methods oi producing coke, which have been 'strictly processes of distillation. In some of these processes continuous chain grate devices are employed, but the heat has always been applied.

from outside the bed and the volatile thus distilled-oif. Care has always been taken that combustion within the be'd did' not occur as this was apparently considered certain to oxidize xed carbon.

' vOiaJsci-s The present invention has for a primary object an improved method and means for controlling a process in which a charge of carbonizable material `maximum output can be achieved without reducing the quality oi' the product-control. oi' the air distribution along the path oi' the charge to a predetermined pattern and adjustment oi' the-air distribution in such a way that the optimum operating conditions as determinedv experimentally can' be reproducibly obtaineda method o! determining and applying optimum conditions for treating diierent types of material.

Tm: Arucmrs' Marston The appncants' method is featured by regulating the air supplied to the material at different stages o! its carbonization, in accordance with the condition oi' the lmaterial at the respective stages. More specifically, the air supply differs from one zone to another inthe path of the bed, the extent of the difference being related to the amount of volatile given oif in the respective zones. Optimum conditions, for treating a particular type oi material, are `arrived at by actually measuring, in experimental Aor pilot runs, the amount of air fed to each zone, comparing the results obtained, and selecting as a pattern i'or operation those which best suit the product desired. The method is also featured by the stabilization of the ow of air to any part of the .bed

against temporary iluctuations in resistance `to flow due to uneven sizes of the material or uneven distribution on the grate. The effect of this treatment is to enable the volatile oi the coal to be driven oil at close to a maximum rate and to the desired extent while at the same time the burning of fixedv carbon is maintained substantially at a minimum.

This control may conveniently be eected by providingbeneath a carrier ior moving the b ed through a carbonizing chamber one or more rows of separate air compartments arranged in the direction of travel oi' the carrier thusproviding a number oi air supply zones beneath the grate. Means is provided for supplying measured amounts of air to each compartment independently oi' the others. Throttling means 'is also pro-v vided in conjunction with each compartment for Vcondition of the bed or `cause such fluctuations and also in the ability to in order to minimize leakages.

tm,- for instance, a liquid column.

sessioni-u maintain a steadier production rate.

Dasclnrrxon The invention, win now be further explained v by reference to a preferred appl'atus for use in carrying it out, shown in the accompanying drawings.inwhich: 4

Figure l is va diagrammatic cross sectionthrough a special coking apparatus conveniently suitable for carrying out the present invention.

Figure 2 is-a diagrammatic elevation. partly in section, showing the apparatus-of Figure 1.

Figure 3 is a atic cross section taken horizontally through the apparatus of Figures 1 and 2 just beneath the bed supporting portion oi the grate.

Referring in more detail to the drawings, A represents the foundation of the apparatus and B the refractory setting. The setting is provided with s fuel feed opening III, and a gas outlet flue lI I. Within the setting is mounted a carrier, in this case a continuous travelling grate l2, of suitable design, conveniently driven by a' standard drive Il. The. setting has a relatively. low ceiling to provide a chamber of limited volume resulting s,sso,voso

in good radiation of heat onto the fuel bed.' In this particular apparatus. the flue II is located remotely from the feed end of the grate and the roof of the oven slopes upwards towards the ilue. but. this arrangement is optional and the nue can be at either end of the chamber and the A chute II leads from a fuel hopper to the opening il. The opening Il is provided with ay gate Il operiltedby suitable mechanism Ii for and lowering it. At the discharge end of the grate I2, and below it is a screw conveyor I-l, for receiving the coke and conveying it to one side of the apparatus. Leading from the conveyor Il l is a chute Il for conveying the coke downwards to a sealing device Il. Below the sealing device is a me'chanismll, for carrying away the coke. The coke can be quenched either in the conveyor I8 or subsequently. The nature of the discharge apparatus is not material to the invention.

Below-the lgrate il are a number of air boxes or compartments Il, Ila, lob. etc. These compertinents each'occupy half of the width of the grate and a portion of the length thereof thus dividing the entire space below the grate both laterally and longitudinally. into a number of air supply sones. While II compartments have been shown,that issixoneachside ofthegrate,itis understood thatthis numbermaybevariedg suit the nature of the apparatus vand the resul desired. Bachcompartmentis entirely separated i'romfthesdlacent onebysidewallsll anda centrewallll. Leadingtoeachsonethereisan duet Il extending fiom an air mlyb! Inch duct includes a metering device, in thiscase a Venturi meter Il. Isch duct also includes an air valve or throttle Il. For l [the 'amount of air at the'meter ll are air lines Il leading to a metering indicator of a suitable Theairisluppliedtotheairsupplyo! l meansA of a blower Il suitably driven as by an perature above the bed-in the dm travel can always be determined.

' Orgasmo Psomlml is ignited andthe chamber gradually brought to the desired operating temperature by running the grate slowly while supplying air from the zones IB, Illa, etc. in suillcient quantities to support the combustion vn to provide the heatl for the process. The chamber being gastight and preferably under positive pressure,

leakages oiair into the chamber abovethe coal bed are minimized. While this starting procedure has4v been found most practical, working conditions may bevarrlved at in any suitable manner.

'I'he speed of the grate and the air -supply is.

slowly increased so that operating temperature isreached gradually to avoid damaging the setting. The grate vl2 is then brought to operating speed, the total amount of air entering the zones 30, 30a, etc. being so regulated through the air` valves 42 that only a portion of the volatile matter from the' lcoal is burned, for example. Just suiiici'ent to evolve the heat necessary to drive oi! the -remainder of the volatile constituents of the charge, before leaving the chamber.

Proceeding in this mannerq-selectivel burning oi?- aportion of the volatile matter in the coalA takes place, and the burning of nxed carbon is reduced .substantially to av minimum. Sufficient heat is generated by the burning of this volatile to remove the remainder, or at least the desired ers of which arerelatively cool.

substantially t0 i llby..

and-huish 'and more towards "since at au times I each zone is regulated amount, to give acke havingv the characteristics sought. The air or other oxygen-containing gas, preferably unheated. into contact with the substantially horizontal bed.,the bottom lay-- air contacting the cool layers of coal, there is no incentive to combustion, which is, therefore, delayeduntil the gir reaches theupperpart .of the bed where the temperature is high. lhis refers to sections of the .bed in their early stages of travel'through the coke chamber. Combustion begins to take 'place at the upper part of the bed. selecting the volatile constituents. This bed: gases, above the bed. The air supply rate is so. regulated-that necessary oxygen constituents, so that As any given portion of the chamber, the wards until nnally it reaches theair supply the bed advances 'According to the requirements of that sone,

o rtl giraer is released from the coal in some Atypes of coal ignite much-faster others. Generally speaking, less volatile at the start and towards `the middle 'of the` t u n less air is required a com e uy the middle. any event, presumlng thatthe total Mits With the 0001 oombustionworksitswaycm A the lower strata.-

isPl'OPOrtlonate theiixed carbon onate to the rate atwhich the volatile gases abo've the various compartments or zones,

-both individually and collectively.

The air iiow to the various compartments is read on the individual indicators Il whichare actuated by the metering devices". The tem,-v

peratures at various points inthe coking chamber are measured by reading imiicatorsconnectedvto the thermometers GII, 60a, etc.

Besides regulation of the flow of air supplied to the respective chambers', control is also exercised to prevent temporary rushes i. e. surges of 'vEample I y According to the nguresshown the follow- A by about feet wide, in an apparatus of proair to any one zone due to changes in resistance tc air now of the bed of coal inthat zone? These changes inl resistance may be caused by bare spots on the grate vor uneven thickness due to irregularities in feeding, uneven size distribution in the coal bed, or clogging of .the air open-I ings in different parts of-the grate. This control is effected by-means of the throttles I2 which restrict" the ilow.v By this means, there are prevented.'rushes of air which would result in a rise in the temperature in one or more zones or cause too` great a proportion of gas and even xed carbon to be burned. The opening'at the throttle has a resistance to the now. of air many-v times that of the grate and coal above-the compartment,v so that a variation in the resistance to'air now in the coal bed itself cannot cause an appreciable variation in the ilow to the compartment and thus throughthe coal bed above it. ilal'or example, if the combined resistance,- that is the pressure drop across the grate and coal bed is of a certain magnitude, the pressure drop across thev restricted opening at the throttle can suitably be several vtimes that magnitude. Thus, the-separate supply of air to each-zone is independent of the resistance -across the bed and grate at that zone.

Each supply is accurately measured. Optimum conditions for treating afspecific material are readily arrived at by carrying out several runs in which the airsupply and other factors are varied. These variable factors are measured, the coke analyzed and the results compared. S- lected measurements are then applied to the regulation ,ofv commercial runs.

. RlsULrs Proceeding as described,v a ne adjustment of apparatus.

` Table I.

L Approximate l Conditions me con 'ma ...nba/minuutu 11s Depth oi coal bed.... h 3% Grate s Percent on l" coal in iced... 45. 0 Percent P. T. M" coal in feed 6.0

r Approximate Temperatures, C. me

Thermometer No. 60.. 925 Thermometer No 1,21) Thermometer No 60h. l, Thermometer No. wc 1 ,.210

I A proximate Approximate Air for combustion 1 r s "me foot. pr

4Total lbs, perminute.. 1.8

A proximate Percentage gl Air for combustion l per of total rapt per n.

Pair'of compartments No. 30 3 3 Pair of comprtments No. 30a 2l 2. 3 Pair of compartments No. 30th.V 26 2. 8 Pair of compartments No. 30e.. Zi 2t Pair of compartments No. 30d.. 22 2. 4 Pair of compartments Ho. Soc.. 5 l .6

the burning of the volatile constituents of the charge is obtained. The conditions are so adjusted that the product discharged from the grate` is coke ofthe desired volatile content. -On

-leaving thecoking chamber.' the coke is hard and it is highly reactive and porous. The unburne'ci volatile matter" driven ofi passes' out through the tlue- Il' to be completely burned to supply heat for a boiler or lime kiln or to be `cooled and collected. Use of the gas for direct heating purposes is considered most practical as it contains a large amount of sensible heat.

ExanPLxs a In order to illustrate the invention further, a series of typical examples will be given of treating various types of coal according to the inven# tion. Itwill, of course, be understood that the figures cited were obtained from carrying out the process on a particular apparatus and are thus not to be taken in a limitingrsense, but `only by way of explanation. n

Moisture Volatilcmatter Ash ber had reached its normal values, the air'enter-v y ingeach compartment was adjusted for steady operation at the. rates 'indicated in the table.V The conditions and results of the run were substantially according to the figures given in Table I and are essentially typical for this particular Result; C

I hours was estimated at 45 tons. The analysis 4 of the coal fed andthe coke produced was as follows:

.Coal

Percent 'Example 1I Table II Conditions A soximengem cm1 ma. ibs/mmm.. 1oz Depth of coal bed st inchee 2% Grate speed lect/hour.. 76 Percent on l"ooalini'eed 3.0 Percent P. T. M" coal in feed 30.0

Temperatures, C Apgoixinme Thermometer No. 60

For the above run the coke producedl in 24 h ours was estimated at 39 tons. The analysis of the coal fed and the coke produced was as follows: l

Coal Coke Percent Percent Moisture 3.6 Moisture 0 Volatile matter ..39. Ash 3.a

Vannini.: Facrons The examples'are representative of characteristic procedures. lIt will o f course be understood.

that there are several variables with which to contend as for instance, thenature of the material treated, the size and particular structure of the apparatus, the thickness oi' the bed, the speed of the grate, i. e. time of treatment, the amount of air supplied. and temperature. The

,Y followingr remarks on variable factors will be of interpretive assistance and taken with the remainder of the disclosure will place the carrying out ofthe invention well within'the understanding of one skilled in the art.

' Cmsonrzni.: Mauritius4 While this disclosure has been framed prin cipally in the termsl of the treatment .of coal to produce coke, it will be understood that various the terms coke," "coking and coking temperature" are used in a generic sense. It is possible to handle varying sizesof material, the lip--v` per limit for substantially optimum results be# ine. in the case of coal,- of the order of s". The minimum size is determined by the ability of the grate to carry a i'lne charge successfully and also by the physical characteristics of the coke desired. Minus.` V4 vinch coal' has been success,-

fully coked by this process.

Tmcxnnss or rmi Ban In connection with bed thickness, the more compact the layer of coal, the better heat insulator it becomes and therefore,'the thinner the layer of coal'will have to be. For a medium sized coal, for example minus about l inch with less than about 20% of through 1/4 inch, a layer .lieved to be better.

a yrelatively thin bed oi coal and a consequently of coal about.2y inchesthick is preferred, and for a smaller coal (rnore than about 20% of fines) a layer of coal about 2%" thickis be- It has been found that when faster grate speed are used, a greater output can types of material other than coal may be oarbonized by the use of the invention.` The specic nature of .this material is relatively 1inimportant within limits. Itwill .be well/understood from this disclosure that the material treated must be a solid capable of being handled in a stoker and must have suflicient volatile to support combustion so as to give of! the heatA required to carry out the process without burning fixed carbon inlexcss of that permissible by the nature andyield of the end product desired. Many .types of coal, wood and-also fuel agglomerates satisfy these criteria. Hence,

be achieved than when a relatively thick layer of coal is used with a slow grate speed. lThe bed thickness can, of course, be varied to suit the results desired.

' GnA'rl: Spaan 'l The grate speed, that is the time of treatment,

can be varied. Of course. sufficient time must be allowed to carbonize the material to the desired extent. In certain cases, where substan-A tially complete carbonization is desired, va speed of about feet per hour has been found feasible in the apparatus described, in such cases the coal being coked in about 9 minutes. preferred speed'is about '75 to about 85 feet per hour in -which case coking any portion of the charge is completed in about 12 to about 15 minutes.v The objection to lowerspeeds-is the decrease in the production rate.

AIR SUPrxfY For maximum production rates, it is desirable' to feed as much air as possible without raising the temperature inany'zone above the limiting temperature .for the apparatus employed, Aand without burning an undesirable amount of fixed carbon. As a general rule, ir the neighborhood of three pounds of air are required for each y pound of coal carbonized.

'I'he relative proportions of the air fed to successive compartments will depend on the type and condition of tl'iev coal', particularly with respect to its screen size and moisture content. In any event, it will be related to the amount of volatile matter given of! above that particular -co compartment, and therefore, in such a manner that uniformity of partial combustion is approached throughout the path of the charge. In the particular apparatus'shown, the air sup-A ply ratio may vary from' practically vzero percent oi the total in the first compartment to about l30% (where there are six pairs of compartments) in the middle compartments when good grades of bituminous coking coal are being f treated.

The following table -typies the. variation of the air supply to different zones of the bed in accordance with four` different 'types of coal. The amounts of air supplied to the diierent zones for the diierent types of coal are based on conditions suitable for the production of good The u 2,880,930 grade coke. The wet and dry coals referred to are extremes in this respect. The dry coal contained less than about 3% moisture, the wet about 10% to about 12% or more of moisture.

Besides the variation of air supply to respective compartments,J the total air supply and grate speed may be .altered to suit the particular. type of material being treated. In principle, for 4'maximum production, conditions are controlled so as to regulate the air so that the temperature in respective zones will be as nearly the same as possible. The 'attempt is also 'to maintain, in any one zone, a uniform temperature.

matter what type oi' coal is being treated. The

supply to each zone 'is actually measured.` 'In this way. air is supplied to the charge at successive stages of carbonization in relation to the requirements oi the charge at those stages.

The speciiic amounts ot air in pounds per suare foot i'or each zone, for 'any one type of coal will vary with the grate speed and thickness ol Ein Psonucrs Extremely accurate control may beexercised over the characteristics of .the end.l product. Control over the amount of volatile left in the coke is particularly accurate. The 'amount of fixed carbon burned can be reduced substantially to a minimum which under practical commercial conditions is below about of the total fixed carbon, as measured by the method of the A. S. T. M. It is possible to reduce the amount of iixed carbon burned tp a lower proportion under `certain conditions, for example by running at a lower rate of production than the maximum, or, by producing a'. volatile content such as a smokeless fuel. 'The gas is highly suitable for various processes rey .quiring heat, such as calcination, steam generathe bed. However. while air has been named as v the source of oxygen, it will be understood that for certain purposes it might'be undesirable,to employ other oxygen-containing gases.

, 'Innnnsml The process is essentially one of high temperature coking, i. e. coking produced by combustion of the volatil where temperatures of from tion, etc.

4 etc.'

Anvmscns The great advantage' of the present invention is in making'it possible, in-a continuous process.' to produce coke oi uniform quantity at a high production rate. Inherently the purpose ofl a carbonization Aprocess of this general nature is to 'burn suiiicient of the volatile matter within and above the coal bed to remove the remainder of the volatile matter by distillation, while reducingfthe burning of the iixed cai-lionV substantially to a Ii the air tsupply required for this result is not properly distributed then more volatile may be burned inone zoneI causing a localized temperature rise.- In such circumstances, damage may be done to the setting of the coking chamber. Due to such mal-distribution of the air supply,nxed carbon of the charge might also be attacked to Yan undesirable extent in this or another zone.

The applicants have discovered that the proportiomng or the airtq the different zones roroptimum 4@cking conditions varies with the nature of the coal, its screen size. moisture content, That is to say,v thosevfactors which will eilect the rate of the partial combustion of the coal have a denite Abearing on the manner in which the total air supply will be divided between the various zones.

For instance, take2 coals'A and B. coal A being more easily burned than coal B. Then for -aboutaoo cjto about 14.00 c. are employed,

distinguished from low temperature coking where lower temperatures are employed. The temperature is controlled in such a way as to stabilize conditions along the path or the `charge and to prevent damage to the setting or to the grate.

- In general, a maximum temperature of about 1200 C. has been found practical for the type of refractory and other materials used in the parlticula'r apparatus on which the examplesl are based. The temperature may be Areduced -considerably, but this would necessitate a longer time for treatment and consequently a lower output. y f

It will be evident from this discussion oi the individual factors meeting the process, that the maintenance oi the grate speed, the total air v supply. the individual air supply to the separate zones, and the amount or coal, fed. must be coordinated to achieve optimum results. l

coal Amore air should be admitted to the rst zones than Vfor coal B, in order to maintain a constant value for the proportion of volatile matter that would be, burned above the bed at these zones. Also, assuming a constant production rate of coke from the two coals, coal A will require less Aair in the ilnal zones than will coal B since its coking is morenearly completed. It the airsupply were not reduced inthe `nnal zones for coal A then iixed carbon would be burned. Fur'- thermore should an amount of air in Aexcess of that requiredto burn the required proportion of volatile matter above any one zone be supplied to any zone, then excessive temperatures will result. Conversely.- if insuillcient air besupplied to any one zone then a proper proportion .of the coking is ot carried out in that zone withv the result tha either the rate of production is reduced or the product will contain partially carbonized coal or green coal or both. Optimum operating conditions. as predetermined experi- 'mentally'. can be tabled or lcharted with respect to themeterV readings for each air compartment andthus used as a guide for the correct operation' for any type or condition or coal. Since it is of ,great advantage to have a 4correct proportioning roduct with a higher residual of the air :supply the maximum benefits are to be obtained when this is held constant and un` affected by continual uctuations in resistance to supply the heat of carbonization, comprising, car'- rying o ut a series or'pilot runs in which car-l air ow of the fuel bed. This is accomplished by the throttles in the air ducts. The effect of these throttles has already been explained.

It will be understood that, without departing from the spirit of the invention or the scope of the claims, various modications may be made in the specific expedients described. The latter are illustrative only and not oiered in a restricting sense, it being desired that only such limitations shall be placed thereon as may be required by the rstate of the prior art.

The sub-titles used throughout the speciilcal tion are merely to simplify reference thereto and shouldvotherwise be disregarded.

We claim:

bonizable material of various types in terms or screen size and moisture content is carbonlzed according to said process to determine the optimum conditions with regard to feeding of air 1. A continuousA process -oi' carbonization wherein carbonizable material is advanced in a progressive path through a carbonizing chamber in the form of a relatively thin bed air is supplied to the bed and volatile constituents of the mate'- rial are burned selectively at least partially -with in the bed to'supply the heat of carbonization,

` comprising, supplying the air independently toV each of a plurality of separate zones in said path in amount to effect combustion ofthe volatiles, throttling each air supply vto reduce surging oi' air to a zone oi lowered resistance-setting the to the respective zones for each type of carboniza' ble material there being maintained in the several zones after an initial zone a high coking temperature which is nearly the same, measuring the characteristics in terms o! screen size and moisture content of a carbonizable material to be carbonized whereby said carbonizable material is typined according tothe pilot runs, and carbonizing in a production run said carbonizablel materialv according to the conditions determined for its carbonization during the pilot runs. Y

.4. A method of applying desirable conditions sto treat a given material in a continuous process ot carbonization wherein said material is passed in a progressive path through a carbonizing chamber in the iorm oi' a relatively thin bed, air i through the chamber in the form of abed, feedtotal supply of air and the speed of progress of the material at rates eiective to reduce combustion ofjthe ilxedcarbn substantially to a desired minimum, setting the air supply to each zone at a rate substantially proportionate to the rateof volatile release in that zone and maintaining a high coking temperature which is nearly the same in the several zones after an initial zone whereby 7 :a substantial uniformity of the proportion of volatile burned is maintained throughout said path. 2. A continuous process of carbonization wherein carbonizable material is advanced in a progressive path through a carbonizing chamber in the form of a relatively thin bed air is supplied 'to the bed and volatile constituents of the material are burned selectively at least partially within the bed to supply the heat of carbonization, comprising, carrying out a pilot run by passing carbonizable material through said path, adjusting the total supply of air and thespeed of progress of the lmaterial to reduce-the combustion oi' the fixed carbon substantially to a predeterminedamount and iurtherapportioning the air, to several separate successive zones in said path in amount to eiect combustion of the volatiles, adjusting the regulated amount oi' air sup- .plied to each zone until it is substantially proportionate to the amount of volatile given oiin that zonel and there exists a high coking temperature which is nearly the same in each of the ing airto a plurality of separate zones underneath the bed in amount to support combustion ofthe volatiles and to supply the heat oi carbonization, adjusting'the air supply until a high coking. temperature isachieved which is nearly the same above the several zones after an initial zone, maintaining the air supply and the speed of progress of the material through said path at rates eective to reduce combustion of the fixed carbon substantially to a desired minimum, and obtaining measurements of the rates of air supply to each compartment under such conditions, carbonizing lsimilar material on a production scale by passing it through the chamber vand supplying air according to said measurements so as to re' produce said conditions.v

5. A method of applying deslrablevconditions for treating a given material in a continuous process of carbonization wherein said material is passed in a progressive path through a carbonizing chamber in the form of a relatively thin bed, air is supplied to the bed and volatile con-` stituents of the material are burned selectively to supply the heat of carbonization, comprising', carrying out several runs in which the material is passed through the chamber in the form of a bed, each run including feeding air to aplurality oi separatezones underneath the bed to support combustion of the volatiles and to supply the heat of carbonization, adjusting they air feed until a high coking temperature is achieved which is nearly the same above the several zones after an initial zone, maintaining the air supply and the tinuously ina progressive path through' a carboni'zing chamber in the form or a relatively thin bed air is supplied to the bed to individual zones in said path in amount to e'ect combustion of y speed of progress of Vthe material through said path at rates effective to reduce combustion of the iixed carbon substantially to a desired minimum, then obtaining measurements of .the rates oi air supply to each zone under such conditions,

uthe measurements being substantially independent of the resistance ofthe grateand the bed to the flow of air therethrough thereby toestablish a pattern of operation for the carbonizat'ion under optimum conditions of that particular type of material. l

6. A continuous process of carbonization wherein carbonizable material isadvanced in a progressive path through acarbonizing chamber 'n.ssopao t Y Y 7 -in the form o! a relatively thin bed.' air is sur'` plied to the bed and volatile constituents of the material are burned selectivelyv at least partially `within the bed to supply the heat of carboniza- `tion. comprising, supplying the air independently toeaoh oi a plurality oi separate zones in said path in amount to eiiect combustion oi 4the'volatiles,setting the air supply to each zone 1 at av rate substantially proportionate to the rate oi i volatiles released from that zone to maintain e. l0-

'CERTIFICATE oFl coRREo'rIoN.

August 7 1916.

Amrum Homann limbbmsiEN,4 ET AL.

IIt ishereby. certified that error appears in the printed specification of the `have numbered patent requi serum, line' 11.9, fenffunnenrabh" ring correction "Letters vPatent: should be read with this correction therein that the sane may conform to the record of the case in the Patent Office.

Signed vand sealed this. 19th lday o (seal) frliarch. A. I).v 1914.6.'

Lenie Frazer F11-.vf Assistant cmissiene of Patents.

as follows: Page 5, first ,read des1rab1e; and that the said 'n.ssopao t Y Y 7 -in the form o! a relatively thin bed.' air is sur'` plied to the bed and volatile constituents of the material are burned selectivelyv at least partially `within the bed to supply the heat of carboniza- `tion. comprising, supplying the air independently toeaoh oi a plurality oi separate zones in said path in amount to eiiect combustion oi 4the'volatiles,setting the air supply to each zone 1 at av rate substantially proportionate to the rate oi i volatiles released from that zone to maintain e. l0-

'CERTIFICATE oFl coRREo'rIoN.

August 7 1916.

Amrum Homann limbbmsiEN,4 ET AL.

IIt ishereby. certified that error appears in the printed specification of the `have numbered patent requi serum, line' 11.9, fenffunnenrabh" ring correction "Letters vPatent: should be read with this correction therein that the sane may conform to the record of the case in the Patent Office.

Signed vand sealed this. 19th lday o (seal) frliarch. A. I).v 1914.6.'

Lenie Frazer F11-.vf Assistant cmissiene of Patents.

as follows: Page 5, first ,read des1rab1e; and that the said 

